Overload relays have long been used in connection with heavy duty electrical machinery driven as, for example, three phase motors. Overload relays are more than simple circuit "interrupters"--they are sensors which, upon determining the existence of an overload or other undesirable circuit condition, break a circuit and in turn provide a control or an indicating function. Because they are typically employed with relatively expensive machinery, it is necessary that they be reliable in operation. As is well-known, reliability is a function of the number of components employed and thus it is highly desirable that the overload relay be of simple construction to achieve enhanced reliability.
At the same time, cost is always of concern. Thus, simplicity is not only desired from the standpoint of improving reliability, it is desired from the standpoint of reducing the cost of the overload relay as well.
It is also desirable that the overload relay be of relatively small size so that it may be easily and conveniently installed in any of a large variety of desired locations with respect to any given piece of machinery.
The present invention is directed to providing an overload relay, and particularly, the mechanical construction thereof, that meets one or more of the above objectives.